The present invention claims a priority based on the Japanese Patent Application No. H11-51730, the contents of which is incorporated hereinto by reference in its entirety.
1. Field of the Invention
This invention relates to a digital camera.
2. Description of Related Art
As it is well known, there are many digital cameras equipped with a distance measuring mechanism for measuring a distance from the camera to the object to automatically focus an optical image of the object passed through a photographing lens onto a light receiving surface of an image pick-up element such as a charge-coupled device (hereinafter referred to as xe2x80x9cCCDxe2x80x9d). In details, in such digital cameras, a distance from the camera to the object is measured by the distance measuring mechanism, and the image pick-up lens is driven in a direction of the optical axis thereof depending on the measured distance to automatically focus the optical image of the object onto the light receiving surface of the CCD. Then, the optical image of the object focused on the CCD is photoelectrically converted into analog signals. The analog signals are converted into digital signals which are then subjected to a prescribed image processing to form image data. The image data are displayed as a photographed image on the liquid crystal display (hereinafter referred to as xe2x80x9cLCDxe2x80x9d).
In the mean time, it has been proposed that a digital camera has not only a function for recording and reproducing the photographed image but also a function for recording measured information on a distance from the camera to the object utilizing the aforementioned distance measuring mechanism.
Conventionally, a digital camera having such a measuring function is disclosed in, for example, Unexamined Laid-open Japanese Patent Publication Nos. 5-153467, 5-153468, 5-79820, 5-56389, 5-45124, 5-45125, 5-30412, 5-26622, 5-22661, 5-18748, 5-14779, etc.
Some of these digital cameras can record the distance information of the object or the size information of the object calculated based on the distance information and the photographing angle information in a recording medium together with the photographed image of the object.
By the way, in order to accelerate a development of a measuring function of such digital cameras, it has been expected that a digital camera which can measure an area of a certain region of a place away from the photographing position, i.e., the camera position, is realized. However, in a digital camera having a conventional measuring function, the function is limited to measure a size of the object. None of the aforementioned prior arts discloses technique for calculating the aforementioned area and recording the calculated information.
Furthermore, none of the prior arts fails to disclose or suggest any concept utilizing a depression angle or an elevation angle of the photographing direction (the direction of the photographing lens). Therefore, it was impossible to calculate the relative position of the measuring point relative to the photographing camera position because it was unable to specify a reference plane such as a horizontal plane in a photographing image. As a result, a height of an object such as a height of a building cannot be measured precisely.
A first object of the present invention is to provide a digital camera by which a user can easily know an area of a certain region of a place away from a photographing position.
A second object of the present invention is to provide a digital camera by which a relative position of a specified measuring point relative to a photographing position can be specified to enable a measurement of a height of an object or the like.
A third object of the present invention is to provide a method to be employed in a digital camera by which an area of a certain region of a place away from a photographing position can easily be known.
A fourth object of the present invention is to provide a method to be employed in a digital camera by which a relative position of a specified measuring point relative to a photographing position can be specified to enable a measurement of a height of an object or the like.
According to a first aspect of the present invention, a digital camera includes a display for displaying an image of an object, a specifying unit for specifying a plurality of measuring points on the display, and a calculator for calculating an actual area of a region surrounded by the plurality of measuring points specified by the specifying unit.
With this digital camera, since the actual area of a region surrounded by the plurality of measuring points specified by the specifying unit can be measured, a user can easily know an area of any desired place away from the photographing position.
According to a second aspect of the present invention, a digital camera includes a display for displaying an image of an object, a specifying unit for specifying a plurality of measuring points on the display, a first detector for detecting a distance from the digital camera to each of the plurality of measuring points of the object, a second detector for detecting a camera angle of each of the plurality of measuring points, a third detector for detecting a photographing direction, and a calculator for calculating a relative position of each of the plurality of measuring points relative to a photographing position, based on detected results of the first, second and third detectors.
With this digital camera, since a reference plane such as a horizontal plane can be specified in a photographing image by detecting the photographing direction, the relative position of a measuring point relative to the photographing position can be measured, which enables a measurement of a height of an object or the like.
According to a third aspect of the present invention, a method for calculating an area of an object in a digital camera includes the steps of displaying an image of the object on a display, calculating a distance from the digital camera to each of a plurality of measuring points specified on the display, calculating an angle of each of the plurality of measuring points relative to said camera, and calculating an actual area of a region surrounded by the plurality of measuring points, based on the calculated distances and the angles.
With this method, since the actual area of the region surrounded by the plurality of measuring points can be calculated, a user can easily know an area of a region of any desired place away from the photographing position.
According to a fourth aspect of the present invention, a method for calculating a relative position of an object relative to a digital camera includes the steps of displaying an image of the object on a display, calculating a distance from the digital camera to each of a plurality of measuring points specified on the display, detecting an angle of each of the plurality of measuring points relative to said camera, detecting a photographing direction, and calculating a relative position of the measuring points relative to the photographing position, based on information on the detected distance of the object, angles and photographing direction.
With this method, since a reference plane such as a horizontal plane can be specified in a photographing image by detecting the photographing direction, the relative positions of the measuring points relative to the photographing position can be obtained. This enables a measurement of a height of an object or the like.